The 22-year-old midfielder joins Guingamp on a free transfer after ending his four-year stay at Danish outfit Brondby IF.
Guingamp, who finished 10th in Ligue 1 last season, announced the deal on their official Twitter account.
Phiri was recently called up to the Bafana Bafana squad for the Africa Cup of Nations qualifier against Nigeria in Uyo on 10 June, to replace the injured Kamohelo Mokotjo
🖋 [OFFICIEL] Signature de Lebogang PHIRI, un international sud-africain à l’En Avant de Guingamp !🚨
Degemer Mat Lebogang ! pic.twitter.com/SkMVBXgOlX
— En Avant de Guingamp (@EAGuingamp) 30 May 2017